Written by
Louise W Lu, PhD, MPH, BMLS
Written/Reviewed by
Lilly (Yutong) Liu, Registered Dietitian, PhD Researcher in Nutrition, University of Auckland
Plastic is everywhere in daily life: a cup of takeaway coffee in the morning, a lunch box at noon, a bubble tea cup in the afternoon, and at home a microwaved storage container. Convenient, yes—but questions never stop: “Does heating release harmful chemicals?”, “Which material is safest for baby bottles and kids’ bowls?”, “Can disposable cups really be reused?”
Remember the formula: Safety = Material × Temperature × Time × Condition.
Wrong material, overheated, left in contact for too long, or a container that’s whitened, scratched, or aged—all can lower the “safety score.”
• “Microwave-safe label means it’s 100% safe” → It only means it meets certain heat resistance standards, not that it’s safe under all foods or oils.
• “Disposable cups can be washed and reused” → Most are PET/#1, not heat resistant, and not suitable for hot drinks.
• “Thicker must be safer” → What matters is the material (e.g. PP/#5, HDPE/#2, Tritan), not thickness.
You can jump directly to:
Next, with the simplest labels and practical rules, we’ll show you which plastics can handle heat, which are only for cold drinks, which to avoid, and the best choices for different groups of people.
1｜Plastic Resin Codes 1–7 & Common Products
On the bottom of many plastic containers, you’ll see a triangle of arrows with a number from 1–7. Many people think this means “recyclable”, but it doesn’t. It’s actually the Resin Identification Code (RIC), which tells you what plastic the container is made from—and different numbers can mean very different safety profiles.
Common products: Bottled water (e.g., Nongfu Spring, Evian), carbonated drink bottles (Coke, Sprite), shelf juices (Minute Maid, Huiyuan).
Features: Clear, light, low cost.
Risks: Intended for single use only. Deforms with heat and may leach under high temperatures. Fine for cold drinks—do not refill with hot water or microwave.
Common products: Milk jugs (Anchor, Meadow Fresh), large bottled water (Wahaha, Nestlé), shampoo bottles (Head & Shoulders, Pantene), family-size yogurt tubs (Yoplait).
Features: Rigid, acid/alkali resistant, low permeability.
Risks: Generally food-safe, but avoid prolonged high-heat exposure.
Common products: Cheap clear storage boxes, some soft water bottles from low-end brands, PVC pipes (home renovation), tablecloths, raincoats.
Features: Flexibility depends on plasticizers; typically less transparent.
Risks: May contain phthalate plasticizers and other chemicals—not recommended for food contact.
Common products: Plastic wrap (Glad, Miao Jie), squeeze ketchup bottles, thin takeout/drink bags, supermarket shopping bags.
Features: Soft, flexible, fairly clear.
Risks: Safe at room temperature, but may leach under high heat. Do not cover oily foods in the microwave.
Common products: Takeout containers (Meituan, Uber Eats), microwaveable lunch boxes (IKEA, Lock&Lock), kids’ tableware (Pigeon, NUK), some baby bottles.
Features: Heat-resistant (often >100 °C), low migration, light yet durable.
Risks: Widely regarded as the safest common food-contact plastic; a top everyday choice.
Common products: Tea/boba cup lids (e.g., HeyTea, CoCo), disposable cutlery (fast-food chains), foam takeout clamshells (night markets, cheap takeaway).
Features: Lightweight, insulating.
Risks: May release styrene under high heat—not recommended for hot foods or drinks.
Common products: Sports bottles (Nike, some Hydro Flask Tritan models), blender cups (Nutribullet, Vitamix), some baby bottles (Dr. Brown’s, Philips Avent).
Features: PC used to be common but may contain BPA; Tritan and similar newer materials are BPA-free and widely used for kids’ cups and premium sports bottles.
Risks: Avoid PC; choose clearly labeled BPA-free Tritan for peace of mind.
Plastic Codes 1–7｜Food-Contact Safety Table
| Code | Material (EN) | Food-Contact Recommendation | Suggested Heat Limit* / Microwave | Common Products (at home/store) | Commonly Leached Toxins | Usage Notes | Safer Alternatives |
|---|---|---|---|---|---|---|---|
| #1 | PET / Polyethylene Terephthalate | ⚠️ OK for cold, short-term; not for hot/heat | ~70 °C; Microwave: ❌ | Bottled water, carbonated drink bottles, shelf-stable juice bottles | Antimony compounds, bromides, ethylene oxide, benzene | Single use only; do not refill with hot water or leave in hot cars; replace if scratched/deformed/odorous. | ✅ PP microwave boxes, borosilicate glass, 304/316 stainless-steel cups |
| #2 | HDPE / High-Density Polyethylene | ⚠️ Safe for cold/room temp; avoid prolonged high heat | ~120 °C; Microwave: ❌ (unless explicitly rated) | Milk jugs, large water containers, shampoo/cleaner bottles, family-size yogurt tubs | Chromium oxide, benzoyl peroxide, hexane residues | Great for storage at cold/ambient temps; avoid long contact with hot oily foods; confirm food-grade labeling. | ✅ PP microwave containers, borosilicate glass |
| #3 | PVC / Polyvinyl Chloride | ☠️ Not recommended | ~70 °C; Microwave: ❌ | PVC pipes, cheap clear boxes, tablecloths, raincoats (mostly non–food grade) | Phthalate plasticizers, benzene, dichloroethane, lead chromate | Avoid any direct food or mouth contact; keep away from heat/oil/acidic foods. | ✅ PP, food-grade PE, borosilicate glass |
| #4 | LDPE / Low-Density Polyethylene | ⚠️ Fine for cold/short-term; avoid heating | ~80 °C; Microwave: ❌ | Plastic wrap, squeeze condiment bottles, thin takeout/shopping bags | Benzene, peroxides, antioxidant/stabilizer residues | Do not use wrap over oily/sugary foods in microwave; keep away from hot pans/ovens. | ✅ Glass boxes with silicone lids, PP microwave boxes |
| #5 | PP / Polypropylene | ✅ Recommended | ~135 °C; Microwave: ✅ (if labeled “Microwave-safe”) | Takeout containers, microwave lunch boxes, kids’ bowls/plates, some baby-bottle parts | Minor additives (antioxidants/lubricants) — low migration when used as directed | Choose food-grade with microwave icon; replace if whitened/aged or heavily scratched; vent lid when microwaving. | ✅ Borosilicate glass (heat-resistant), 316 stainless (not for microwave) |
| #6 | PS / Polystyrene | ☠️ Not for hot foods/drinks | ~90 °C; Microwave: ❌ | Foam clamshells, disposable cutlery, boba/tea lids | Styrene, benzene, tert-butyl hydroquinone | Avoid hot soups and fried foods; never microwave; if unavoidable, use only for cold drinks and discard after use. | ✅ PP containers, molded-pulp cups (water-based lining), glass/stainless steel |
| #7-PC | PC / Polycarbonate | ☠️ Not recommended | ~135 °C; Microwave: ❌ | Older sports bottles, older baby bottles, some rigid reusable tumblers | BPA, BPS and other bisphenols | Avoid for food contact, especially hot or acidic drinks; retire older PC items. | ✅ Tritan (BPA-free), PP, borosilicate glass |
| #7-Tritan | Tritan™ Copolyester | ✅ Safe for cold/room temp; ⚠️ caution with high heat | ~90–100 °C; Microwave: ❌ (most not rated) | Sports bottles, blender jars, many kids’ cups | BPA/BPS-free; generally low additive migration | Avoid prolonged boiling/oily high-heat; follow brand cleaning instructions. | ✅ PP for microwaving; borosilicate glass for high-heat cooking |
| #7-PLA | PLA / Polylactic Acid (bioplastic) | ⚠️ OK for cold; not for hot | ~60 °C; Microwave: ❌ | Compostable cups, disposable straws, some “eco” takeout bowls | Softens/warps at heat; limited migration data | Use for cold foods only; avoid hot soups/drinks; don’t leave in hot cars. | ✅ Paper cups (water-based lining), PP, glass |
* Heat limits are conservative values from public sources/typical labeling for home use and risk screening. Always follow your product’s packaging instructions.
Authors:
Lilly (Yutong) Liu
Registered Dietitian, PhD Researcher in Nutrition, University of Auckland
Lilly is a New Zealand Registered Dietitian and PhD candidate at the University of Auckland. She specialises in elderly and post-operative nutrition care through her clinical work with DietRight, and her research focuses on biomarkers and nutrition strategies in pancreatic diseases. With experience in hospital-based nutrition, RedCap data management, and bilingual study coordination, she is committed to delivering evidence-based, culturally informed nutrition solutions.
